MERCURY INSTRUMENTS
ANALYTICAL TECHNOLOGIES
VM-3000
Mercury Vapor Monitor
Continuous mercury measurement
in air and other gases
Direct reading mercury vapor meter
● Portable, integrated battery for 6 hours operation
● Proven reliable detection method: UV absorption
● Easy operation
● Automatic zero adjustment
● Measuring ranges 0-100 / 0-1000 / 0-2000 µg/m3
● High resolution 0.0001 mg/m3
● Data logger integrated
●
Fields of application
The VM-3000 Mercury Tracker serves for continous measurement of the mercury concentration in air and
other gases in laboratory as well as industry and mobile applications.
It has a wide variety of applicationsons:
● work place monitoring (threshold limit value)
●exhaust air monitoring in mercury recovery plants
● emission monitoring in the chemical industry
● ground air screening of contaminated soil
● quality control of hydrogen and natural gas
● detector for laboratory applications
Measuring principle
The mercury concentration is measured in an optical cell made of fused silica. A maintenance-free membrane pump continuously feeds the sample gas to the optical cell where light absorption measurement
takes place at a wavelength of 253.7 nm. This so-called “cold vapor atomic absorption spectroscopy
(CVAAS)” measuring method is extremely sensitive for mercury determination and has been used successfully for many years. In contrast to the occasionally propagated atomic fluorescence spectroscopy (AFS)
method it is low in interference and requires neither an amalgamation step nor expensive noble gases as
carriers.
Reference UV Detector
Temperature Control
Optical Cell
UV Source
(EDL)
UV Detector
Beam
Splitter
Cell Heating
Pinch Valve
Zero Gas
Filter
Long-Life
Membrame
Pump
Particulate
Filter
Sample in
Sample out
VM-3000 flow chart
Analytical Performance
The VM-3000 uses a high-frequency driven electrodeless Hg low pressure (EDL) lamp as UV source. It generates emission lines of an extremely narrow bandwidth which are congruent with the absorption lines of
the Hg atoms. Cross-sensitivities are thus minimized. The extremely high stability of the UV source in the
VM 3000 is a result of the reference beam feedback control method. Total background noise is less than
0.1 µg/m3. To prevent temperature drift both the lamp unit and the detectors are temperature-stabilized.
Because the optical cell is heated the VM-3000 is insensitive to water vapor.
Precise and proven technique:
Mercury Vapor Monitor
VM-3000
Special Features
● Metal housing with sturdy handle
● Option: Rack version with mounting brackets for 19” racks
● Membrane pump with long service life
● Input filter with teflon membrane
● Stable optical bench
● Factory-calibrated
Easy to operate
The user controls the VM-3000 by menu-guided inputs via a waterproof membrane keypad. After switchon the light source is stabilized (approx. 1 - 15 minutes). When the measurement mode is started, a zero
adjustment is first carried out automatically. Then the analyzer switches to measurement and continuously indicates the measured mercury concentration of the gas as a numerical value and a graphic bar.
The following settings are possible in the “parameters” menu: duration and repeat interval of the zero
adjustment, selection of the concentration unit (µg/m3 or ppb), measuring range (0.1-100, 0-1000,
0-2000 µg/m3), input of three different alarm levels, calculation of a mean value over three freely
selectable time intervals, printer activation, and, if required, a sample dilution factor.
Display and Output of
Measurements
The result of the measurement is displayed on
an LCD in real time, both numerically and graphically and is output as an electrical signal of 4-20
mA. The device has outputs for alarm, status and
measurement values for full integration in plant
control systems. The device also has a serial interface (RS 232) for data collection on a PC.
Graphical and numerical display of results in realtime
Extensions
The VM-3000 Mercury Vapor Monitor is the
basic model of our modular system for mercury analytics. An optional reaction unit and
activation of the relevant software turn it
into a laboratory unit for liquid samples.
Multiplexer operation
A multiplexer unit can be connected for
automatic monitoring of several measurement points. See information in special
broschure.
Self Diagnosis System
Extension: Laboratory Analyzer for Mercury LabAnalyzer-254
If an important component of the VM-3000 malfunctions the user is warned via the display (blinking messages: clean cell, lamp, low battery, alarm) and via output signals.
Battery Operation
For operation independent from mains power the VM-3000 is also available with a built-in rechargable
battery and a charger unit. This option allows mobile battery-powered applications of up to approx. 5
hours.
Data Logger Function
A data logger function can be integrated into the VM-3000 as an option. Up to 30000 readings can be
stored in the data memory. The logging interval can be set from 1 - 16 seconds revealing a total recording
capacity of 4-60 hours. The stored data can be read out with a PC using the serial interface of the VM-3000
according RS232 standard.
Wavelength:
253,7 nm
UV source:
Electrodeless low-pressure mercury lamp
Stabilization:
reference beam and thermal
Optical cell:
fused silica (Suprasil), 23 cm long
Optical cell heating:
approx. 70° C
Measuring range:1...100µg/m3; 1...1000µg/m3; 1 - 2000µg/m3
Sensitivity:
0.1 µg/m3
Response time:
1 sec
Computation of mean value:
autom. via three freely
selectable time intervals
Alarm:
when concentration is exceeded,
3 levels are programmable
Status alarms:
measuring cell soiled, battery state, UV source
Control pad:
waterproof membrane keypad
Measurement display:
Graphic display with background lighting
Signal outputs:
4...20 mA for recorder;
RS 232 bidirectional for PC, data logger etc.,
parallel for printer
Pump:
membrane pump, approx. 2 L / min.
optional Flow meter with alarm message
Filter: PTFE, 1 µ, 47-50 mm diameter
Power supply:
110 ... 240 V/(50/60 Hz)
Battery operation:
optional, 12 V batteries integrated, 6 h capacity
or external DC Source
Data logger-function:
Up to 30000 readings capacity
Power consumption:
40 W
Dimensions:
45 x 15 x 35 cm (W x H x D)
Weight:
approx. 7 kg
Mercury Instruments GmbH
Analytical Technologies
Distributed by:
Liebigstrasse 5
85757 Karlsfeld (Germany)
Tel.: +49 (0)8131 - 50 57 20
Fax: +49 (0)8131 - 50 57 22
[email protected]
www.mercury-instruments.de
© 2000 Mercury Instruments · VM3000 08-2000
Measuring principle:UV-Absorption
Specifications subject to change!
VM-3000 Mercury Vapor Monitor
Technical Specifications